Linear motor assembly and a method for mounting said assembly

ABSTRACT

The invention relates to a linear motor, in which the permanent magnets ( 5 ), the support ( 1.1, 1.2 ) for the permanent magnets ( 5 ) and the fixing elements ( 4 ) of the support ( 1.1, 1.2 ) are completely covered. The covering consists of cover strips ( 7 ) that are detachably applied next to the permanent magnets ( 5 ) in the border region of the support ( 1.1, 1.2 ) and that cover the fixing elements ( 4 ), in addition to the fixing boreholes ( 3 ) of the support ( 1.1, 1.2 ). The permanent magnets ( 5 ) are covered by a cover plate ( 10 ), which lies on top of the cover strips ( 7 ).

[0001] The invention relates to a linear motor assembly in accordance with the preamble of claim 1, and to a method for mounting this assembly.

[0002] A linear motor is employed as the drive mechanism in various fields, for example in machine tools, automatic fitting or bonding devices and conveying installations.

[0003] A linear motor consists of an assembly with a support, to which several permanent magnets are attached in the drive direction and define a track for a runner which can be moved in relation to it. This assembly is also called a secondary element. The runner acts in a reciprocating manner with the magnets and translates this reciprocal action into a translatory motion.

[0004] In the course of operating the linear motor it is possible for foreign objects, such as chips or tool elements to be introduced between the runner and the permanent magnets and to become stuck there. If the assembly consists of several lined-up supports, these foreign objects can also become stuck at the gaps between joints of the supports. To prevent such sticking, it has already been proposed in accordance with DE 198 53 250 to cover the permanent magnets by means of a magnetic cover plate, and to pour synthetic resin into the sides of the permanent magnets.

[0005] Drill holes are provided in the support and in the synthetic resin material for mounting this assembly. This has the disadvantage that foreign objects can be come stuck in these holes.

[0006] It is therefore the object of the invention to embody an assembly of a linear motor consisting of a support and several permanent magnets in such a way that a dependable operation is assured and a simple manufacture is made possible.

[0007] This object is attained by means of an assembly having the characteristics of claim 1.

[0008] It is a further object of the invention to disclose a method for mounting an assembly of a linear motor, by means of which the assembly can be fastened on a machine element in a simple manner, and fastening takes place in such a way that the fastening means do no interfere with the operation of the linear motor.

[0009] This object is attained by means of a method having the characteristics of claim 12.

[0010] Advantageous embodiments are disclosed in the dependent claims.

[0011] The invention will be explained by means of exemplary embodiments.

[0012] Shown are in

[0013]FIG. 1, a view from above on several supports,

[0014]FIG. 2, a cross section II-II in accordance with FIG. 1,

[0015]FIG. 3, a view from above on the supports with cover strips,

[0016]FIG. 4, a cross section IV-IV in accordance with FIG. 3,

[0017]FIG. 5, a view from above on the supports in the completely covered state,

[0018]FIG. 6, a cross section VI-VI in accordance with FIG. 5,

[0019]FIG. 7, a longitudinal sectional view through a cover strip,

[0020]FIG. 8, a second fastening option for the cover strip, and

[0021]FIG. 9, a third fastening option for the cover strip.

[0022] A view from above on an assembly, also called a secondary element, of a linear motor is represented in FIG. 1. This assembly consists of several supports 1.1, 1.2, which can be mounted in a row on a machine element 2. As a rule, the supports 1.1, 1.2 consist of a ferromagnetic material. Each support 1.1, 1.2 has a plurality of bores 3, which are spaced apart from each other and which are engaged by screws 4 for fixing the supports 1.1, 1.2 in place on the machine element 2. Several permanent magnets 5 are arranged one behind the other on the supports 1.1, 1.2 and act reciprocally with a runner 6, only schematically represented in FIG. 2, and cause a movement of the runner 6 in relation to the supports 1.1, 1.2 in the displacement direction X.

[0023] A cross section II-II in accordance with FIG. 1 is represented in FIG. 2. It can be seen that the bores 3 have been cut so deeply into the supports 1.1, 1.2 that, following the screwing into place of the supports 1.1, 1.2 on the machine element 2 (first mounting step), the heads of the screws 4 have been completely received in the bore 3.

[0024] Following the mounting step represented in FIGS. 1 and 2—fastening the supports 1.1 and 1.2 on the machine element 2—a second mounting step takes place, which is represented in FIGS. 3 and 4.

[0025] In this second mounting step a cover strip 7 is fastened on the edge areas of the supports 1.1 and 1.2, which respectively extend in the displacement direction X (track of the runner 6). Such a cover strip 7 is schematically shown enlarged in FIG. 7. It is made of a non-magnetic material, in particular plastic (injection-molded element) and has protrusions 8, with which it is wedged into the bores 3 on the support 1.1, 1.2.

[0026] The outer diameter of the protrusions 8 constituting the clamping elements corresponds to the inner diameter of the bores 3, so that the bores 3 constitute a fit at the joints for the protrusions 8. By providing several—in particular two—protrusions 8 spaced apart from each other in the displacement direction X, each cover strip 7 is automatically aligned when being pressed on its support 1.1, 1.2. In view of the mechanics of manufacturing it is particularly advantageous if the clamping elements, or protrusions 8, are formed in one piece with the cover strip 7.

[0027] It is particularly advantageous if the cover strips 7 form a conduit 9, which is used for receiving a covering tape 10, which is to be attached in a third mounting step. So that the covering tape 10 rests solidly, the height of the cover strips 7 in the resting area of the covering tape 10 corresponds to the height of the permanent magnets 5. For forming the conduit 9, by means of which the covering tape 10 is aligned, the cover strips 7 each have a lateral strip 11, whose height corresponds to the thickness of the covering tape 10. The assembly which is completely mounted in this way is represented in FIGS. 5 and 6.

[0028] If the covering tape is a sheet metal piece of a ferromagnetic material, for example special steel, no additional steps for fixing the covering tape 10 in place are necessary, since it automatically adheres to the permanent magnets 5 by means of the magnetic force. The cover plate 10 is preferably inserted continuously into the conduits of the supports 1.1 and 1.2, which are lined up with each other in the displacement direction X, for example by being pulled off a roll.

[0029] A cover 7 and 10 for the bores 3, the screws 4 and the permanent magnets 5 is created in this way in a simple manner. The individual elements of this cover in the form of cover strips 7 and the covering tape 10 can be provided to the user of the linear motor, who only inserts them when the supports 1.1, 1.2 are mounted on a machine element. Easy mounting and also removal is possible. The cover strips 7 can be lined up at any arbitrary length as a function of the number of supports 1.1, 1.2 to be mounted.

[0030] The surface of the supports 1.1, 1.2 pointing in the direction of the runner 6 is completely covered and level, so that entering foreign objects no longer have a chance of getting stuck. Thus, the operational dependability of the linear motor is assured.

[0031] The invention is explained by means of the example of two supports 1.1 and 1.2, however, it can also be successfully employed with only one support, or with more than two supports.

[0032] As represented in FIG. 8, the cover strip 7 can also be fixed in place at the outer circumference of the screw 4. In this case no bore 3 need to be provided for receiving the head of the screw 4, as schematically represented in FIG. 9. In place of a protrusion 8, a recess 12 is provided in the cover strip 7 for clamping, which grippingly encloses the head of the screw 4.

[0033] In the above explained example, the length of a cover strip 7 is matched to the length of the supports 1.1, 1.2 in that the length of a cover strip 7 corresponds to the length of a support 1.1, 1.2. However, a cover strip 7 can also be selected to be longer, in particular extend over several supports 1.1, 1.2. It can also be advantageous if the cover strip 7 consists of a bendably elastic material —in particular plastic—, so that the cover strip 7 can be rolled up, the same as the covering tape 10, and covers a multitude of fastening elements in one piece by being unrolled. In this case being capable of being rolled up means that the elasticity of the material has been selected to be such that a bending radius of approximately 30 cm is possible, so that when rolled up, great lengths of the cover strip 7 can still be manipulated. 

1. A linear motor assembly, having a sequence of permanent magnets (5) on a support (1.1, 1.2), fastening elements (4), by means of which the support (1.1, 1.2) can be fastened on a machine element (2), and a cover (10) for the permanent magnets (5), characterized in that the assembly has at least one cover element (7), with which the fastening elements (4) are covered.
 2. The assembly in accordance with claim 1, characterized in that the cover element is a cover strip (7), which is releasably fastened on the support (1.1, 1.2) next to the permanent magnets (5).
 3. The assembly in accordance with claim 2, characterized in that at least one clamping element (8) is formed on the cover strip (7), which is clamped on a corresponding fitting (3) of the support (1.1, 1.2), or of a fastening element (4).
 4. The assembly in accordance with claim 3, characterized in that several clamping elements (8), which are spaced apart from each other, are formed on the cover strip (7) in the direction (X) of the track of the runner (6), each of which is clamped to a corresponding fitting (3) of the support (1.1, 1.2), or of the fastening element (4).
 5. The assembly in accordance with claim 3 or 4, characterized in that the cover strip (7) has at least one protrusion (8) constituting the clamping element, which engages a corresponding recess (3) in the support (1.1, 1.2) and in this way clamps the cover strip (7) to the support (1.1, 1.2).
 6. The assembly in accordance with claim 5, characterized in that the fastening elements are screws (4), and that respective recesses (3), which are clampingly engaged by the protrusion (8), are provided for receiving the screws (4) on the support (1.1, 1.2).
 7. The assembly in accordance with one of the preceding claims, characterized in that cover strips (7) extending in the direction (X) of the track of a runner (6), are respectively fastened in the two edge areas of the support (1.1, 1.2).
 8. The assembly in accordance with claim 7, characterized in that the permanent magnets (5) are covered by means of a covering tape (10), which partially rests on the cover strips (7), wherein the cover strips (7) have a height in the resting area which corresponds to the height of the permanent magnets (5), and outside of the resting area have a height corresponding to the height of the permanent magnets (5) plus the thickness of the covering tape (10).
 9. The assembly in accordance with claim 8, characterized in that the covering tape (10) is a sheet metal plate (10) made of ferromagnetic material.
 10. The assembly in accordance with claim 8 or 9, characterized in that a plurality of lined up supports (1.1, 1.2) and cover strips (7) are provided, and that the covering tape (10) extends uninterrupted over several supports (1.1, 1.2).
 11. The assembly in accordance with one of preceding claims 2 to 10, characterized in that the cover strip (7) is embodied to be bendably elastic and can be rolled up.
 12. A method for mounting an assembly of a linear motor on a machine element (2), having the following process steps: a) fastening at least one support (1.1, 1.2) with a plurality of permanent magnets (5) on the machine element (2) by means of a plurality of fastening elements (4). b) placing cover elements (7) on the support (I. 1, 1.2), wherein the cover elements (7) cover the fastening elements (4), c) covering the permanent magnets (5) by means of a covering tape (10).
 13. The method in accordance with claim 12, characterized in that the cover elements are cover strips (7), which are releasably clamped to the support (1.1, 1.2). 